Apparatus for determining and recording the dust content of flue gas



Oct. 12, 1954 H HOLBY W. APPARATUS FOR DETERMINING AND RECORDING THE DUST CONTENT OF FLUE GAS Filed Dec. 18, 1951 INV EN TOR.

Patented Oct. 12, 1954 AEPARATUS FOR DETERMINING AND BE- CORDING THE DUST CONTENT OF FLUE Worrell Hansell Holby, New Rochelle, N. Y., assignor to The General Power Plant Corporation, Ossining, N. Y., a corporation of New York Application December 18, 1951, Serial No. 262,296

2 Claims. 1 This invention relates to apparatus for determining and recording the dust content of flue gas.

Manufacturing plants, such as steel mills, have large quantities of gas coming from the blast furnaces, which have considerable fuel value. However, this gas contains a great deal of very abrasive dust and grit which is carried over from the coke and iron ore and which causes clogging and wear in pipes, valves, etc.

To make this gas available it is put through a scrubber and then through an electrostatic precipitator. This cleans the gas and removes most of the dust and the cleaned gas is saturated with water.

This invention was developed for the purpose of continuously monitoring and recording the gas in order to keep track of the dust content. This problem is rendered difficult because of the amount of water vapor in the gas and because the gas is under positive pressure and is poisonous.

This invention has for its salient object to provide simple and practical apparatus for continuously and accurately analyzing and recording the dust content of flue gas.

Another object of the invention is to provide apparatus of the character described, involving the use of a photo-electric cell and energizing lamp and so constructed and arranged that the lenses will remain clean and clear.

Another object of the invention is to provide apparatus of the character described, involving the use of a photo-electric cell and energizing lamp and so constructed and arranged that the lenses will remain clean and clear but the gas sample will not be diluted.

Another object of the invention is to pro vide apparatus of the character described, so constructed and arranged that the analyzer and recorder can be easily and quickly zeroed and calibrated.

Another object of the invention is to provide apparatus so constructed and arranged that the length of the gas sample being analyzed can be regulated so that the length can be reduced for very dense or dirty gas.

Further objects of the invention will appear from the following specification taken in connection with the drawings whichform a part of this application, and in which Fig. 1 is a longitudinal sectional elevation illustrating apparatus embodying the invention;

Fig. 2 is a diagrammatic elevational view showing the circuits for the apparatus and illustrating diagrammatically the operative parts thereof;

Fig. 3 is an end elevation taken substantially at right angles to Fig. l; and

Fig. 4 is a sectional elevation showing means for adjusting the energizing lamp relative to the lens,

In the particular embodiment of the invention illustrated in the drawings there is shown a sampling tube or cylinder I0 having heads 12 and S3 at the ends thereof. The gas to be sampled is conducted from a gas main 15 through a conduit It to a conduit H and thence through a conduit E8 to the approximate longitudinal center of the tube It. the conduit 18 into the tube is shown at 19. Outlet ports 2!! and 2! are provided at the end portions of the sampling tube 18 and the gas escaping through the outlet ports is burned by a gas flame 22 from a gas cock 23.

A drain pipe 25 is connected to the conduit H and connects at its bottom with a pipe 26 which also communicates a drain pipe 21 which, at its other end, communicates with the sampling tube It.

The conduit I! on opposite sides of the center thereof has connected thereto manometers v 30 and 3E and also valves 32 and 33. At the right of the center, viewing Fig. 1, there is connected to the conduit l! a thimble 34 and a meter 35 which are used in the usual manner to measure and weight measured quantities of gas.

The head I2 of the tube or cylinder it has mounted therein a tube 40, which has mounted in the outer end thereof an energizing lamp ll and a reference cell i2 which is adapted to receive the light rays directly from the lamp. However, in order to vary the amount of light reaching the reference cell from the energizing lamp, adjustable Polaroid filters 43 and M are interposed between the lamp and the reference cell.

Within the tube is adjustably mounted a telescoping tube 45 having a lug 46 at the inner end thereof which is threaded and is mounted on a rotatable screw Ll! which is carried by the heads l2 and 3 and extends throughout the length of the tube It. The outer end of the screw 4'! has mounted thereon a head 38 by means of which it can be rotated.

The head l3 has mounted therein a tube 50 on the outer end of which is mounted an analyzing photo-electric cell 5!. Within the tube 5 is slidably mounted a telescoping tube 52 having a lug 53 provided with a threaded opening and mounted on the screw 41. The threads at one end of the screw 47 will be left hand threads and those at the other end will be right hand threads, so that when the screw is rotated the telescoping tubes 45 and 52 will be moved simultaneously toward and away from each other.

The purpose of providing the adjustable telescoping tubes is to vary the length of the gas column to be analyzed. For instance, when the The inlet opening from gas is very'dense onheavy-with dust,.thetubes 45 and 52 areamove'd toward each other. so that'the rays between the lamp and the energizing cell will pass through a shorter length of gas column. When the dust content is less the length. of the gas column analyzed will be greater and to accomplish this the telescoping tubes 45' and'52 will be moved away from each other.

One of the objects of the invention is to prevent dust and moisture from obscuring the'lenses: in the lamp tube and analyzing cell tube and this is accomplished in the following; manner. Apipe 55 is connected to a source of compressed air supply and communicates through a pipe 55 with-a pipe 51. The ends of the pipe. 51 are connected by pipes 58 and 59 tothe tubesv lit and 58 adjacent the outer ends thereof, thereby introducing clean air into: the tubesail audit and also into the telescopingtubes lfi and 52. This air will keep the tubes: All, 45 and Eli, 52 clean and'freefrom dust and mois-ture. The air will pass inwardly through. the tubes and will. pass from the. tube H3 through. the. outlets 20' and 2i to the atmosphere. Thus, the lamp tube and analyzing tube will be kept clean. and, furthermore, the gas sample-in the tube ill will not be diluted by the clean air.

Theconduits fia an'd 59 in the; embodiment'of. the invention-shown have mounted therein sight flow indicators fi l and: 61 and valves 62. and 63.

In Figs. 1 and the. recorder R, which makes a record of the dust content in the gas main as determined bythe analysis made in the sampling tube, is, controlled and operated by the difference in output. between the analyzing cell El and the reference cell 42. The analyzing cell receives the light from the lamp 4i through the sample of gas being analyzed in the tube 10.. On the other hand, the reference cell iz receives its light directly from the energizing lamp 41..

The circuit'utilizedinthe apparatus is illus trated diagrammatically in Fig. 2. In this circuit the positiv terminal of the analyzingcell Si is.

connected to the negative terminal of the reference. cell 42 by'a wire 65. The positiveterminal of thereference. cell 42 is connected to an adjustable contact 65 of abridge circuit. In this circuit a variable resistance wire Sl is connected at one end. by a Wire 6% to the negative terminal of the. analyzing cell 5!. The other end of the variable resistance wire -6l' is connected. through a resistance B3 to the wire 65. The. recorder R is connected across the Wires 85. andBB.

The recorder is zeroed by adjusting the circuit.

so that the output of the cells 42, and 5! is equal when the sampling tube. 10-. is. filled with clean. air. This is accomplished by first adjusting the Polaroid. filters 43 and-4d so thatless light will reach the reference cell 22 than will, reach the analyzing cell 5! when the sampling tube is filled with clean. air and the lampis at the focal point of the lens L disposed in the lamp tube 40. The two cells 52 and Eli are then brought into balance by moving the lamp 4! ahead or the focus point of the lens L, thus dispersing or scattering the light on the analyzing cell 51. This is accomplished by an adjusting screw ll accessible at theback ofthe casing of the energizing lamp 4 I As hereinbefore stated, in order to analyze or measure. very dirty gas, it is necessary to reduce the length of the sample in order to keep the reading. on the chart. This is accomplished by sliding the telescoping sleeves or tubes 65 and 52 inwardly by the rotation of the screw 81. "In this way the length of the sample can be reduced from sixty inches to twenty inches. The sensiti ityfof the recorder'R can be increased by adding. resistance 69 to the end of the resistance 61, thus increasing the pen travel by unit of dust in the sample.

The recorder R- must be calibrated for each type of gas and for each setting of the samplin tube, that is, eachvariation in length of the sample to be analyzed. The width or length of the sample will 'be altered in accordance with the density of the dust content. The calibration of the recorder is accomplished by measuring the actual solid contentol the gas, using the thimble 36 and meter 35 in the usual manner.

By introducing the gas to be analyzed into the longitudinal center of the sampling tube Ill and byintroducing clean air in the outer ends. of, the tubes 49 and 533, the lenses in the lamp and analyzing cell tubes will be maintained clear and will not be affected by any moisture or dust which i present in the sampling tube. Moreovergbl introducing the air in the manner described, the sample being tested will not be diluted by the. air used to keep the tubes it. and 56 clear and: free frommoistureanddust.

Moreover, the circuit above described and the. use of the reference cell in the manner outlined eliminates any error which might be caused by line voltage variations in the energizing lam-p circuit.

Although one specific embodiment of the invention has been particularly shown and described it will be understood that th invention is capablev of modification and that changes in the various cooperating parts may be made without departing from the spirit or scope of the invention as expressed in the following claims.

What I claim is:

1. Gas analyzing apparatus comprising a sampling tube, means for introducing gas to be analyzed into the central portion of the tube, gas. and air exhaust conduits at the end portionsof the tube, a lamp tube extending longitudinally into one end of the sampling tube, an energizing lamp at the outer end of said lamp. tube, a. third tube extending into the other end of thesampling. tube, a photo-electric analyzing cell at. the outer end of said last named tube, and means for. introducing air into said lamp tube and analyzing cell tube. adjacent the lamp and cell.

2. Gasanalyzingapparatus comprising a sampling tube, means for introducing gas to be analyzed into the central portion of the tube, gas and. air exhaust conduits at the end, portions of the tube, a lamp tube extending longitudinally into one end or the sampling tube, an energizing lamp. at the outer end ofsaid lamp tube, a third tube extending into the other end of the sampling tube, a photo-electric analyzing cell at th outer endof said last named tube, adjusting means for changing the distance between the inner ends. of the tubes extending into the sampling tube, and means for introducing air into. said lamp tube and analyzing cell tube adjacent the lamp and cell.

References Cited in the file of thispatent UNITED STATES/PATENTS Number Name .;Date.

2,040,265 McNeill et al "May: 1-2, 1936.

FOREIGN PATENTS Number Country .Date

981,636 France Jan. 17,1951 

